Two-way interactive cable television systems are known for transmitting entertainment, information and data signals over a cable facility toward a plurality of users. Data may be transmitted and addressed to a particular subscriber over a separate data channel or over a so-called "n-band" data channel. In a downstream direction. addressed control data may represent services authorized to a particular terminal or control commands to that terminal. In an upstream direction from a terminal to the service provider or system manager location, control data may represent selections made by a user in response to a polling request or at the time of user selection.
In a hotel environment, the system manager delivers video signals, e.g., television programming, to user terminals located, for example, in various hotel rooms over cable lines, and the system manager also transmits digital messages To receivers at each room location. Similarly, information and data generated at each room are transmitted upstream to the system manager via the cable.
It is known in the prior art to provide an interactive terminal at a user location including a local processor for controlling access to a host computer located at the system manager location and a local data store connected to the local processor. Such terminals also normally consist of a display for displaying messages to the user or details of the transaction being conducted, and a keyboard or remote key pad comprising a number of keys by which the user can enter data and initiate functions.
Typically, a central data storage is provided at the system manager location for storing a complete data base, and a smaller subset of that data base is maintained in the local store at the user terminal. Because faster response times can be achieved if a requested transaction can be completed without the need for repeatedly accessing the central data base, configuration of the local store becomes an important design consideration. Prior methods of local storage management have been based upon last use or recency of use, and systems are also known in which those items in the data base most frequently requested by the user terminals are retained in the local store. These methods have not, however, been entirely satisfactory, and have not uniformly achieved the desired reduction in response time. Accordingly, there is a need for a more efficient technique for choosing data items to be stored in a local storage of an interactive terminal system.